I guess if you do burn a DVD, you can't overwrite the data in any way, in that whatever is burned onto the DVD is permanent?

The basic idea behind reading optical media is that a laser is fired at the disc, and depending on whether the laser reflects back, that part of the disc is considered a 1 or a 0. Retail discs are pressed from a master (they're not burned at all), and contain pits that deflect the laser away from the reading sensor. Recordable discs are in fact burned, and the burned spots become opaque and stop reflecting the laser, so these spots have the same effect as the pits in a pressed disc, as far as the reader is concerned. Rewritable media is more complex, it's made of a material that can change states multiple times.

tokumaru wrote:

Is this mini DVD-R technology different than what the GameCube normally uses?

Physically, the difference is that GameCube discs are pressed, and DVD-R is burned. In addition to that, there appears to be differences in the protocol, according to the page tepples linked to. I do know that the protection can be circumvented though, because there are people running games off of mini DVD-Rs.

The basic idea behind reading optical media is that a laser is fired at the disc, and depending on whether the laser reflects back, that part of the disc is considered a 1 or a 0.

It almost seems like a miracle that they are that reliable in that regard. I've never quite understood as to how programs never catastrophically fail from reading off of something as seemingly unreliable as that. (Just one bit could mean either jumping back to the start of a loop or running off into nowhere...)

Like you said though, the fact that if it's pressed or burned is irrelevant, so it all comes down to this protocol thing. If you bought new DVD to be burned, would the area for protocol be blank or would it already be filled out, because in that case, you're out of luck...

Just one bit could mean either jumping back to the start of a loop or running off into nowhere...

Well, it's not like these 0s and 1s are raw data... Here's what Wikipedia says about CDs:

Quote:

The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a series of zeros. There must be at least two and no more than ten zeros between each one, which is defined by the length of the pit. This in turn is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc.

I have no idea what most of that means, but it's clear that the data goes through a lot of transformations so it can be read from the disc more reliably.

I've never quite understood as to how programs never catastrophically fail from reading off of something as seemingly unreliable as that.

It's called Reed-Solomon coding. If some bytes are illegible, the drive's controller does various polynomial voodoo in a finite field to guess the missing bytes. The same principle is used in 2D barcodes such as QR codes.

Just one bit could mean either jumping back to the start of a loop or running off into nowhere...

Well, it's not like these 0s and 1s are raw data... Here's what Wikipedia says about CDs:

Quote:

The pits and lands themselves do not directly represent the zeros and ones of binary data. Instead, non-return-to-zero, inverted encoding is used: a change from pit to land or land to pit indicates a one, while no change indicates a series of zeros. There must be at least two and no more than ten zeros between each one, which is defined by the length of the pit. This in turn is decoded by reversing the eight-to-fourteen modulation used in mastering the disc, and then reversing the cross-interleaved Reed–Solomon coding, finally revealing the raw data stored on the disc.

I have no idea what most of that means, but it's clear that the data goes through a lot of transformations so it can be read from the disc more reliably.

In short, from memory, each pit / opaque spot on a disc indicates an XOR with the previous bit state. That's what I remember from my A+ class form six years ago.

I do know that the protection can be circumvented though, because there are people running games off of mini DVD-Rs.

Most GameCube consoles via software can affect the DVD drive controller to enable a standard DVD reading mode. I think later ones and all Wii consoles cannot do this via software anymore but there is a hardware (modchip) method of basically doing the same thing to enable reading standard DVDs.

Prior to this the GameCube actually had an interesting piece of software using Phantasy Star Online and the Broadband Adapter that allowed you to stream ISO images over your network to your GameCube. The only problem is the transfer rate or the method of transferring data did not work well with audio and video streams in many games.

I think later ones and all Wii consoles cannot do this via software anymore but there is a hardware (modchip) method of basically doing the same thing to enable reading standard DVDs.

I believe older Wiis allowed this, as there used to be a piece of homebrew called DVDX that installed a hidden channel enabling DVD Video commands to be sent to the drive. This was supplanted by a later release of Homebrew Channel, which incorporated the ability to do this (via the HW_AHBPROT flag) internally. Newer Wiis have drive firmware that will not read from any disc that is not an official Nintendo optical disc (GC or Wii) without a drivechip mod.

I considered doing this, but optical drives have the annoying tendency to fail, and considering how old the GameCube is, I wouldn't expect a used one to last very long. If only you didn't need to use a disc in order to boot the Game Boy hardware...

Old topic, but this info wasn't mentioned in it so far, so:There exists a GC drive replacement that takes SD cards. It was developed after the Wii had already come out, and mainly used for piracy of course, but if you're worried about the optical drive flaking out, try finding one of those. I forget what it was called though.

I considered doing this, but optical drives have the annoying tendency to fail, and considering how old the GameCube is, I wouldn't expect a used one to last very long. If only you didn't need to use a disc in order to boot the Game Boy hardware...

For that matter, if you're using a modchip or Datel Media Launcher, there is no reason to use the GBP disc: GBI is better in pretty much every respect. Lower latency and native 240p support. All versions support using a GBA as a controller.

There are three builds:

ULL: Tries to very closely match the GBA refresh rate, and has essentially zero lag. Unfortunately many displays/upscalers either won't sync with this, or show monochrome, and occasional tearing will happen on all displays when the GBA and GC drift out of sync. But, 240p/480p output and no lag is reaaaally nice.

LL: A bit less of a close match to the GBA native refresh rate. More compatible, and solves the tearing by adding a rolling framebuffer for 1-2 frames of lag. Still has 240p support (not sure about 480p).

Regular: Standard refresh rates so works on any display, supports various types of scaling/borders/networking/colour adjustments/on-screen menu/etc. but has 2-3 frames of lag at 60Hz and 1.5-2 frames of lag at 120Hz (which requires HDMI mod, IIRC).

Personally, my PVM works great with ULL, and my particular GBP/GC exhibit the tearing only relatively rarely and for a relatively short amount of time, making it a tolerable tradeoff for the reduced lag.

EDIT: But yes, the GBP is generally cheaper to buy without the disc than with, since the disc is a lot more rare than the GBP. Since I planned to use GBI from the start, that didn't concern me, and I did burn a GBP disc anyhow for the heck of it.

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